scholarly journals Formation of the crater suevite sequence from the Chicxulub peak ring: A petrographic, geochemical, and sedimentological characterization

2021 ◽  
Author(s):  
Pim Kaskes ◽  
Sietze J. de Graaff ◽  
Jean-Guillaume Feignon ◽  
Thomas Déhais ◽  
Steven Goderis ◽  
...  
Keyword(s):  
Compositional Data ◽  
Ocean Water ◽  
New Classification ◽  
Planktic Foraminifera ◽  
Data Set ◽  
Scientific Drilling ◽  
International Ocean Discovery Program ◽  
Chicxulub Impact ◽  
The Impact

This study presents a new classification of a ∼100-m-thick crater suevite sequence in the recent International Ocean Discovery Program (IODP)-International Continental Scientific Drilling Program (ICDP) Expedition 364 Hole M0077A drill core to better understand the formation of suevite on top of the Chicxulub peak ring. We provide an extensive data set for this succession that consists of whole-rock major and trace element compositional data (n = 212) and petrographic data supported by digital image analysis. The suevite sequence is subdivided into three units that are distinct in their petrography, geochemistry, and sedimentology, from base to top: the ∼5.6-m-thick non-graded suevite unit, the ∼89-m-thick graded suevite unit, and the ∼3.5-m-thick bedded suevite unit. All of these suevite units have isolated Cretaceous planktic foraminifera within their clastic groundmass, which suggests that marine processes were responsible for the deposition of the entire M0077A suevite sequence. The most likely scenario describes that the first ocean water that reached the northern peak ring region entered through a N-NE gap in the Chicxulub outer rim. We estimate that this ocean water arrived at Site M0077 within 30 minutes after the impact and was relatively poor in rock debris. This water caused intense quench fragmentation when it interacted with the underlying hot impact melt rock, and this resulted in the emplacement of the ∼5.6-m-thick hyaloclastite-like, non-graded suevite unit. In the following hours, the impact structure was flooded by an ocean resurge rich in rock debris, which caused the phreatomagmatic processes to stop and the ∼89-m-thick graded suevite unit to be deposited. We interpret that after the energy of the resurge slowly dissipated, oscillating seiche waves took over the sedimentary regime and formed the ∼3.5-m-thick bedded suevite unit. The final stages of the formation of the impactite sequence (estimated to be <20 years after impact) were dominated by resuspension and slow atmospheric settling, including the final deposition of Chicxulub impactor debris. Cumulatively, the Site M0077 suevite sequence from the Chicxulub impact site preserved a high-resolution record that provides an unprecedented window for unravelling the dynamics and timing of proximal marine cratering processes in the direct aftermath of a large impact event.

scholarly journals Probing the hydrothermal system of the Chicxulub impact crater

2020 ◽  
Vol 6 (22) ◽  
pp. eaaz3053 ◽  
Author(s):  
David A. Kring ◽  
Sonia M. Tikoo ◽  
Martin Schmieder ◽  
Ulrich Riller ◽  
Mario Rebolledo-Vieyra ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Earth’S Crust ◽  
Scientific Drilling ◽  
Chicxulub Impact Crater ◽  
Earth's Crust ◽  
International Ocean Discovery Program ◽  
Geomagnetic Polarity ◽  
Chicxulub Impact ◽  
The Impact ◽  
Yellowstone Caldera

The ~180-km-diameter Chicxulub peak-ring crater and ~240-km multiring basin, produced by the impact that terminated the Cretaceous, is the largest remaining intact impact basin on Earth. International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition 364 drilled to a depth of 1335 m below the sea floor into the peak ring, providing a unique opportunity to study the thermal and chemical modification of Earth’s crust caused by the impact. The recovered core shows the crater hosted a spatially extensive hydrothermal system that chemically and mineralogically modified ~1.4 × 105 km3 of Earth’s crust, a volume more than nine times that of the Yellowstone Caldera system. Initially, high temperatures of 300° to 400°C and an independent geomagnetic polarity clock indicate the hydrothermal system was long lived, in excess of 106 years.

Introduction

2021 ◽  
Author(s):  
Wolf Uwe Reimold ◽  
Christian Koeberl
Keyword(s):  
Electron Backscatter Diffraction ◽  
Planetary Science ◽  
Impact Cratering ◽  
Scientific Drilling ◽  
Meteorite Impacts ◽  
International Ocean Discovery Program ◽  
The University ◽  
Backscatter Diffraction ◽  
Chicxulub Impact ◽  
The Impact

ABSTRACT This paper does not have an abstract. CONFERENCE The Large Meteorite Impacts and Planetary Evolution Conference VI (LMI VI) took place between 30 September and 3 October 2019 on the campus of the University of Brasília (UnB) in Brasília, Brazil. This series of essentially quintennial conferences has been a mainstay for three decades. It was initiated with the aim to review major research outcomes, share ideas, and fertilize new collaborations in the impact cratering and planetary science fields. The timing for LMI VI, related to the state of impact cratering research, was a good one. For example, the studies resulting from the important IODP-ICDP (International Ocean Discovery Program–International Continental Scientific Drilling Program) project, in which a deep drill core was retrieved from the peak ring of the Chicxulub impact structure—the smoking gun for the Cretaceous-Paleogene (K-Pg) boundary impact event coincident with the mass extinction at that time—were nearing completion and could be presented, in part, at LMI VI. Numerous other advances in impact research had been made in the preceding years (for example, state-of-the-art microstructural studies on accessary minerals with electron backscatter diffraction [EBSD]) and were extensively discussed at the conference. And, finally, interest in impact cratering has significantly increased in recent years, not only...

Assessing the performance of a foraminifera-based transfer function to estimate sea-level changes in northern Portugal

2011 ◽  
Vol 75 (1) ◽  
pp. 278-287 ◽  
Author(s):  
Eduardo Leorri ◽  
Francisco Fatela ◽  
Alejandro Cearreta ◽  
João Moreno ◽  
Carlos Antunes ◽  
...  
Keyword(s):  
Transfer Function ◽  
Sea Level ◽  
Cross Validation ◽  
Compositional Data ◽  
Depositional Environments ◽  
Sea Level Changes ◽  
Concentration Data ◽  
Data Set ◽  
Northern Portugal ◽  
The Impact

AbstractWe assessed the performance of a transfer function model for sea-level studies using salt-marsh foraminifera from two estuaries of northern Portugal. An independent data set of 12 samples and 13 sub-fossil samples from a core were used to evaluate if reconstructions and errors derived from current models are adequate. Initial transfer function models provided very strong results as indicated by cross-validation (component 2; r2 = 0.80–0.82; RMSEP ranged from 10.7 to 12.3 cm) and improved its performance by ca. 10% when sample size reached ca. 50. Results derived using an independent test data set indicate that cross-validation is a very effective approach and produces conservative errors when compared to observed errors. We additionally explored the possible effect of transforming the concentration data into percent in the error estimations by comparing the results obtained based on the use of both concentration and compositional data. Results indicate that this type of transformation does not affect the performance of the transfer function. Results derived from a reconstruction of sub-fossil samples from a core indicate that high-resolution sea-level reconstructions are possible, but show that depositional environments have to be selected carefully in order to minimize the impact of possible taphonomical loss.

Tracing shock-wave propagation in the Chicxulub crater: Implications for the formation of peak rings

Geology ◽  
2020 ◽  
Vol 48 (8) ◽  
pp. 814-818
Author(s):  
Matthias Ebert ◽  
Michael H. Poelchau ◽  
Thomas Kenkmann ◽  
Bennet Schuster
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Shock Wave Propagation ◽  
Data Set ◽  
Scientific Drilling ◽  
Thrust Zone ◽  
Chicxulub Crater ◽  
International Ocean Discovery Program ◽  
Impact Simulations ◽  
Block Sizes

Abstract The Chicxulub crater (Yucatán Peninsula, Mexico) is considered exceptional in many scientific aspects; morphologically it is the only known impact structure on Earth with a well-preserved peak ring. Recent drilling (International Ocean Discovery Program–International Continental Scientific Drilling Program Expedition 364) into this topographic feature provides insights into the structural properties and complex formation of a peak ring. By means of U-stage microscopy on shocked quartz grains from the granitic section of the recovered drill core, orientations of feather features (FFs) were determined and local principal axis of stress (σ1) orientations of the shock wave were derived. The FF orientations are strongly confined to a radially outward trend (WNW) relative to the crater center, which emphasizes a link between FF formation and the direction of shock-wave propagation. Thus, FFs represent an excellent tool as a stress-orientation indicator for the shock wave. Our microstructural data set shows that the granitic basement of the peak ring between ∼750 and ∼1200 m below seafloor behaved as a semi-coherent block above an imbricate thrust zone, and underwent both rotation and local folding during cratering. This validates the block sizes of acoustic fluidization employed in most Chicxulub-scale impact simulations. The folding of the upper part of the granitic basement may have developed by either (1) compression of the crater wall at the transient cavity and/or (2) dragging by the centripetal flow of the overlying crater material.

scholarly journals Complications During Maxillary Sinus Augmentation Associated with Interfering Septa: A New Classification of Septa

2017 ◽  
Vol 11 (1) ◽  
pp. 140-150 ◽  
Author(s):  
Tassos Irinakis ◽  
Valentin Dabuleanu ◽  
Salwa Aldahlawi
Keyword(s):  
Bone Loss ◽  
Maxillary Sinus ◽  
Retrospective Chart Review ◽  
Marginal Bone Loss ◽  
New Classification ◽  
Sinus Augmentation ◽  
Membrane Perforation ◽  
The Impact ◽  
Sinus Membrane

Purpose: A new classification of maxillary sinus interfering septa based on its orientation is presented along with its relationship to the prevalence and severity of sinus membrane perforations. Additionally, the impact of membrane perforation on post-operative complications and marginal bone loss during the first year of loading is evaluated. Materials & Methods: Retrospective chart review of 79 consecutive sinus lift procedures with lateral window technique and 107 implants. Preoperative Cone Beam Computed Tomography (CBCT) images were evaluated for the incidence and the direction of maxillary septa. Chart notes were examined for the incidence of membrane perforation and postoperative complications. Measurements of mesial and distal marginal bone levels and average bone resorption adjacent to each implant were calculated in intraoral radiographs taken at implant placement and during follow up appointments. Results: Interfering septa were identified in 48.1 percent of sinuses. 71.1 percent of them had the septum oriented in a buccal-lingual direction (Class I). The overall incidence of membrane perforation was 22.8 percent, and the presence of an interfering septum on CBCT scan was found to be significantly associated with the occurrence of a sinus membrane perforation (P<0.001). The mean implant marginal bone loss for sinuses, which did not experience a membrane perforation, was 0.6±0.8mm, compared with 0.9 ± 0.9 mm for the sinuses that did experience a perforation (P = 0.325). Conclusion: Septa should be identified, classified and managed with a meticulous attention to technical details. A classification based on the septal orientation is proposed since the orientation of the septa can complicate the surgical procedure and requires modification of the surgical technique.

Shock-deformed zircon from the Chicxulub impact crater and implications for cratering process

Geology ◽  
2021 ◽  
Author(s):  
Jiawei Zhao ◽  
Long Xiao ◽  
Zhiyong Xiao ◽  
Joanna V. Morgan ◽  
Gordon R. Osinski ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermal Evolution ◽  
Ground Truth ◽  
Large Impact ◽  
Impact Melt ◽  
Collapse Model ◽  
Chicxulub Impact Crater ◽  
International Ocean Discovery Program ◽  
Chicxulub Impact ◽  
The Impact

Large impact structures with peak rings are common landforms across the solar system, and their formation has implications for both the interior structure and thermal evolution of planetary bodies. Numerical modeling and structural studies have been used to simulate and ground truth peak-ring formative mechanisms, but the shock metamorphic record of minerals within these structures remains to be ascertained. We investigated impact-related microstructures and high-pressure phases in zircon from melt-bearing breccias, impact melt rock, and granitoid basement from the Chicxulub peak ring (Yucatán Peninsula, Mexico), sampled by the International Ocean Discovery Program (IODP)/International Continental Drilling Project (IODP-ICDP) Expedition 364 Hole M0077A. Zircon grains exhibit shock features such as reidite, zircon twins, and granular zircon including “former reidite in granular neoblastic” (FRIGN) zircon. These features record an initial high-pressure shock wave (&gt;30 GPa), subsequent relaxation during the passage of the rarefaction wave, and a final heating and annealing stage. Our observed grain-scale deformation history agrees well with the stress fields predicted by the dynamic collapse model, as the central uplift collapsed downward-then-outward to form the peak ring. The occurrence of reidite in a large impact basin on Earth represents the first such discovery, preserved due to its separation from impact melt and rapid cooling by the resurging ocean. The coexistence of reidite and FRIGN zircon within the impact melt–bearing breccias indicates that cooling by seawater was heterogeneous. Our results provide valuable information on when different shock microstructures form and how they are modified according to their position in the impact structure, and this study further improves on the use of shock barometry as a diagnostic tool in understanding the cratering process.

DNA-hybridisation Studies of Marsupials and their Implications for Metatherian Classification

1997 ◽  
Vol 45 (3) ◽  
pp. 211 ◽  
Author(s):  
John A. W. Kirsch ◽  
Mark S. Springer ◽  
François-Joseph Lapointe
Keyword(s):  
Monophyletic Group ◽  
Pairwise Comparisons ◽  
South American ◽  
New Classification ◽  
Data Set ◽  
Hierarchical Levels ◽  
Dna Hybridisation ◽  
Taxon Tree ◽  
The Individual

We review past DNA-hybridisation studies of marsupials and present a reanalysis of the data, utilising results from our and additional studies to formulate and rationalise a new classification of Marsupialia. In the reanalysis, 13 individual DNA-hybridisation matrices, many lacking some pairwise comparisons, were sutured in stages to provide the basis for generating a tree of 101 marsupials plus an outgroup eutherian; a fourteenth matrix provided data for a tree including eight additional eutherians and a monotreme. Validation was achieved by jackknifing on taxa for each matrix as well as on tables combining two or more matrices generated during assembly of the 102-taxon data set. The results are consistent with most conclusions from the individual studies and dramatise the unevenness of hierarchical levels in current classifications of marsupials. In particular, the affinities of the American marsupial Dromiciops gliroides with, and the distinctness of marsupial bandicoots from, Australasian metatherians are reaffirmed, while opossums are shown to be as internally divergent as are most members of the order Diprotodontia. Calibration of the 102-taxon tree and dating of the major dichotomies suggest that no extant marsupial lineage originated before the latest Cretaceous, and that all of them together with most South American and all Australasian fossils should be recognised as a monophyletic group contrasting with a largely Laurasian (if possibly paraphyletic) taxon. These inferences, together with the details of the phylogeny, mandate that the misleading ‘Australian’ v. ‘American’ distinction be abandoned, even as a geographic convenience.

scholarly journals The first day of the Cenozoic

2019 ◽  
Vol 116 (39) ◽  
pp. 19342-19351 ◽  
Author(s):  
Sean P. S. Gulick ◽  
Timothy J. Bralower ◽  
Jens Ormö ◽  
Brendon Hall ◽  
Kliti Grice ◽  
...  
Keyword(s):  
Sediment Accumulation ◽  
Thick Layer ◽  
Coarse Grained ◽  
Scientific Drilling ◽  
Impact Melt ◽  
Global Cooling ◽  
Polycyclic Aromatic ◽  
International Ocean Discovery Program ◽  
Geologic Record ◽  
The Impact

Highly expanded Cretaceous–Paleogene (K-Pg) boundary section from the Chicxulub peak ring, recovered by International Ocean Discovery Program (IODP)–International Continental Scientific Drilling Program (ICDP) Expedition 364, provides an unprecedented window into the immediate aftermath of the impact. Site M0077 includes ∼130 m of impact melt rock and suevite deposited the first day of the Cenozoic covered by <1 m of micrite-rich carbonate deposited over subsequent weeks to years. We present an interpreted series of events based on analyses of these drill cores. Within minutes of the impact, centrally uplifted basement rock collapsed outward to form a peak ring capped in melt rock. Within tens of minutes, the peak ring was covered in ∼40 m of brecciated impact melt rock and coarse-grained suevite, including clasts possibly generated by melt–water interactions during ocean resurge. Within an hour, resurge crested the peak ring, depositing a 10-m-thick layer of suevite with increased particle roundness and sorting. Within hours, the full resurge deposit formed through settling and seiches, resulting in an 80-m-thick fining-upward, sorted suevite in the flooded crater. Within a day, the reflected rim-wave tsunami reached the crater, depositing a cross-bedded sand-to-fine gravel layer enriched in polycyclic aromatic hydrocarbons overlain by charcoal fragments. Generation of a deep crater open to the ocean allowed rapid flooding and sediment accumulation rates among the highest known in the geologic record. The high-resolution section provides insight into the impact environmental effects, including charcoal as evidence for impact-induced wildfires and a paucity of sulfur-rich evaporites from the target supporting rapid global cooling and darkness as extinction mechanisms.

Maastrichtian crustacea (Brachyura: Decapoda) from the Ocozocuautla Formation in Chiapas, southeast Mexico

2001 ◽  
Vol 75 (2) ◽  
pp. 319-329 ◽  
Author(s):  
Francisco J. Vega ◽  
Rodney M. Feldmann ◽  
Pedro García-Barrera ◽  
Harry Filkorn ◽  
Francis Pimentel ◽  
...  
Keyword(s):  
New Genus ◽  
New Genus And Species ◽  
Associated Fauna ◽  
Planktic Foraminifera ◽  
Impact Site ◽  
Index Species ◽  
The Caribbean ◽  
Chicxulub Impact ◽  
The Impact ◽  
Southeast Mexico

More than thirty complete specimens ofCarcineretes planetariusVega, Feldmann, Ocampo, and Pope, 1997, a member of the extinct decapod family Carcineretidae, have been collected from the upper part of the Ocozocuautla Formation in Chiapas, southeast Mexico. Stratigraphic occurrences ofCarcineretesin the Caribbean Province suggest that this crab should be regarded as an index fossil for the early Maastrichtian. Six samples of this species may represent individuals that died during molting. The sudden disappearance of this family at the end of the Maastrichtian and its restricted paleobiogeographic distribution in the vicinity of the impact site suggest that the Carcineretidae may have been affected by the Chicxulub impact. Other decapod specimens collected from the same localities were assigned to the Xanthidae;Parazanthopsis meyapaquensisnew genus and species, andMegaxantho zoque, new genus and species, are described. They constitute the second and third reports of Cretaceous xanthid crabs from Mexico. A lagoonal paleoenvironment is suggested, based on associated fauna and flora. Occurrences of index species of benthic and planktic foraminifera along with that of diagnostic rudist species confirm an early Maastrichtian age.

scholarly journals A Study on COVID-19 Incidence in Europe through Two SEIR Epidemic Models Which Consider Mixed Contagions from Asymptomatic and Symptomatic Individuals

2021 ◽  
Vol 11 (14) ◽  
pp. 6266
Author(s):  
Raúl Nistal ◽  
Manuel de la Sen ◽  
Jon Gabirondo ◽  
Santiago Alonso-Quesada ◽  
Aitor J. Garrido ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Social Isolation ◽  
Epidemic Models ◽  
New Classification ◽  
Transmission Rates ◽  
Intervention Measures ◽  
The World ◽  
The Impact

The impact of the SARS-CoV-2 (COVID-19) on the world has been partially controlled through different measures of social isolation and prophylaxis. Two new SEIR (Susceptible-Exposed-Infected-Recovered) models are proposed in order to describe this spread through different countries of Europe. In both models the infectivity of the asymptomatic period during the exposed stage of the disease will be taken into account. The different transmission rates of the SEIR models are calculated by considering the different locations and, more importantly, the lockdown measures implemented in each region. A new classification of these intervention measures will be set and their influence on the values of the transmission rates will be estimated through regression analysis.

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